The Actinomyces constitute a significant proportion of the complex microbial flora that inhabits the human oral cavity ..sup.16, 3 The more facultative to aerobic species within this genus, A. viscosus and A. naeslundii have become the subject of increasing study within the past two decades, because of their suspected role in periodontal infections which affect the cervical areas of the teeth and the supporting tissues..sup.13, 22, 14 Clinical studies on the relationship of these organisms to oral disease and to the oral ecology in general have been hampered by the lack of reliable culture techniques. Differential media have been described in recent years for the selective cultivation of oral Actinomyces from clinical samples..sup.6, 1, 15 However, these media, which rely on either fluoride or cadmium to supress other members of the gram-positive oral flora, can be inhibitory to some strains of Actinomyces and are only partially selective.
The present invention describes the development of a practical selective medium for the detection and enumeration of A. viscosus and A. naeslundii. Improved recovery of these two species, as well as greater selectivity of the medium, was attained by the use of a combination of selective agents.